The autooxidation of solid isotactic polypropylene, inhibited with three di
fferent additives, a phenol, an amine and a nitroxyl radical as well as the
ir binary and tertiary mixtures was investigated. Noticeable synergy effect
s were observed for phenol-amine and phenol-nitroxyl radical combinations;
these effects were especially high in the region of low inhibitor concentra
tion-the so-called subcritical region. A mathematical model is proposed for
evaluation of the contribution of each inhibitor to the induction period.
The value of such a description was confirmed by comparison of the experime
ntal and calculated data. (C) 1999 Elsevier Science Ltd. All rights reserve
d.